feat(user): 新增邮箱注册与验证码发送功能

- 新增 UserRegisterDTO 及 /user/register 接口
- 集成 MailerSend，异步发送 6 位验证码邮件
- 添加 RedisUtil 缓存验证码 10 分钟
- 补充 SEND_MAIL_FAILED、CONFIRM_PASSWORD_NOT_MATCH 错误码
- 关闭 Spring Security CSRF 与表单登录，放行 /user/register
- AppleService 移除 @AllArgsConstructor，改用 @Resource 注入

src/main/java/com/yolo/keyborad/utils/SendMailUtils.java

@@ -0,0 +1,57 @@
+package com.yolo.keyborad.utils;
+
+import com.mailersend.sdk.MailerSend;
+import com.mailersend.sdk.MailerSendResponse;
+import com.mailersend.sdk.Recipient;
+import com.mailersend.sdk.emails.Email;
+import com.mailersend.sdk.exceptions.MailerSendException;
+import com.yolo.keyborad.common.ErrorCode;
+import com.yolo.keyborad.exception.BusinessException;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.scheduling.annotation.Async;
+import org.springframework.stereotype.Component;
+
+/*
+ * @author: ziin
+ * @date: 2025/12/3 20:43
+ */
+@Component
+@Slf4j
+public class SendMailUtils {
+
+    @Value("${mail_access_token}")
+    private String accessToken;
+
+    @Async("mailTaskExecutor")
+    public void sendEmail(String userName,String userMail,Integer code ) {
+
+        Email email = new Email();
+
+        email.setFrom("verify code", "MS_JqR6MO@no-replay.loveamorkey.com");
+
+        Recipient recipient = new Recipient(userName, userMail);
+
+        email.addRecipient(userName,userMail);
+
+        email.setSubject("no-replay");
+
+        email.setTemplateId("k68zxl28q79lj905");
+
+        email.addPersonalization(recipient, "code", code);
+
+        MailerSend ms = new MailerSend();
+
+        ms.setToken(accessToken);
+
+        try {
+            MailerSendResponse response = ms.emails().send(email);
+            log.info("邮件发送成功 messageId={}", response.messageId);
+        } catch (MailerSendException e) {
+            log.error("邮件发送失败: {}", e.getMessage());
+            // 异步任务不能再抛业务异常，避免影响主业务流程
+            // 如果需要，你可以把失败记录写入 DB 或重试队列
+        }
+    }
+
+}